Cellular Mechanisms of Renal Interstitial Fibrosis

描述（由申请人提供）：肾脏疾病的进展会导致常见的后果，包括间质纤维化、肾小球硬化、血管狭窄和肾衰竭，最终需要透析或肾移植。肾肌成纤维细胞是肾纤维化过程中对基质积累最负责的细胞类型。尽管有大量关于肾纤维化过程后期间质肌成纤维细胞基质合成机制的数据，但缺乏有关在基质积累之前涉及肌成纤维细胞侵入血管周围和间质空间的最早细胞事件的信息。提出实验来检查加速肾纤维化模型中肌成纤维细胞侵入（迁移和增殖）的机制，其中肌成纤维细胞首先起源于血管周围和肾小球周围区域。我们的中心假设是：在肾纤维化进展早期，PDGFR-2 和 TGF-β 受体的激活通过 Rho/ROCK 调节的 ROS 生成和 PI3-激酶/Akt、MAPK (ERK1/2) 信号通路的转导，诱导成纤维细胞迁移和增殖到肾小管周围间质中。设定了以下目标： 目的 1. NAD(P)H 氧化酶衍生的 ROS 参与肾纤维化过程早期肌成纤维细胞间质的侵蚀；目标 2. ROS 诱导的间质肌成纤维细胞迁移、增殖和基质合成是 PDGFR-2 和 TGF-β 受体激活的结果；目标 3. 通过 PDGFR-2 和 TGF-2 受体产生 ROS，调节 SMAD2/3、Rho/ROCK、ERK1/2 和 Akt 信号级联，启动间质肌成纤维细胞迁移、增殖和基质合成。 PDGF BB 和 TGF2-1 在血管疾病中启动 ROS 生成。实验旨在严格检查 NAP(P)H 氧化酶和相关的 phox 亚基在 ROS 生成、PDGFR-2 和 TGF-2 受体激活以及体外和体内肌成纤维细胞迁移、增殖和基质合成的信号通路中的作用。具体而言，将检查 NAD(P)H 氧化酶途径（Nox2 和 Nox4 以及 phox 亚基）在 PDGFR-2 和 TGF-2 受体转导 SMAD、Rho/ROCK、PI3K 和 ERK1/2 肾肌成纤维细胞激活调节中的作用。这些研究将为肾纤维化早期阶段肌成纤维细胞激活机制提供急需的见解。 公共健康相关性：迄今为止，大多数关于肾间质纤维化的研究都集中在与基质积累相关的晚期变化，而很少关注肌成纤维细胞侵入间质（迁移和增殖）的早期事件。了解纤维化发生前肌成纤维细胞侵蚀的机制可能会导致慢性肾病早期治疗的新疗法。该应用重点关注活性氧 (ROS) 在纤维化初始阶段早期肾肌成纤维细胞侵蚀中的作用。

DESCRIPTION (provided by applicant): Progression of renal disease leads to common consequences including interstitial fibrosis, glomerulosclerosis, vascular narrowing, and renal failure, ultimately requiring dialysis or renal transplantation. The kidney myofibroblast is the cell type most responsible for matrix accumulation during renal fibrosis. Although there is a large amount of data on mechanisms of interstitial myofibroblast matrix synthesis late in the course of renal fibrosis, information on the earliest cellular events involving myofibroblast encroachment into the perivascular and interstitial spaces prior to matrix accumulation is lacking. Experiments are proposed to examine mechanisms of myofibroblast encroachment (migration and proliferation) in a model of accelerated renal fibrosis in which myofibroblasts first originate from perivascular and periglomerular regions. Our central hypothesis is: Activation of PDGFR-2 and TGF-beta receptor induces fibroblast migration and proliferation into the peritubular interstitium via Rho/ROCK modulated ROS generation and transduction of PI3-kinase/Akt, MAPK (ERK1/2) signaling pathways early during the progression of renal fibrosis. The following aims are set: Aim 1. NAD(P)H oxidase-derived ROS are involved in myofibroblast interstitial encroachment early during the course of kidney fibrosis; Aim 2. ROS-induced interstitial myofibroblast migration, proliferation and matrix synthesis is a consequence of PDGFR-2 and TGF- beta receptor activation; Aim 3. ROS generation through PDGFR-2 and TGF-2 receptor regulate SMAD2/3, Rho/ROCK, ERK1/2 and Akt signaling cascades, initiating interstitial myofibroblast migration, proliferation, and matrix synthesis. PDGF BB and TGF2-1 initiate ROS generation in vascular disease. Experiments are designed to critically examine a role for NAP(P)H oxidase and associated phox subunits in ROS generation, PDGFR-2 and TGF-2 receptor activation and signaling pathways on myofibroblast migration, proliferation and matrix synthesis in vitro and in vivo. Specifically, a role for the NAD(P)H oxidase pathway (Nox2 and Nox4 and phox subunits) will be examined in PDGFR-2 and TGF-2 receptor transduction of SMADs, Rho/ROCK, PI3K, and ERK1/2 regulation of activation of kidney myofibroblast. These studies will provide much needed insight on mechanisms of myofibroblast activation during the early stages of renal fibrosis. PUBLIC HEALTH RELEVANCE: To date, the majority of research on renal interstitial fibrosis has focused on late changes associated with matrix accumulation, with little attention on early events of myofibroblast encroachment (migration and proliferation) into the interstitium. Understanding the mechanisms of myofibroblast encroachment before fibrosis occurs could lead to new therapies in the early treatment of chronic renal disease. This application focuses on a role for reactive oxygen species (ROS) in renal myofibroblast encroachment early during the initial stages of fibrosis.